Braving sub-zero temperature and patiently crossing the strict security barriers, hundreds of thousands of people on Tuesday converged at the National Mall in Washington before dawn, hours ahead of the swearing-in ceremony of Barack Obama as the 44th President of the United States.

An estimated two million people have thronged Washington to witness the momentous occasion, when an African-American would enter the White House, which itself was built by black slaves.

Image: The sun rises behind the US Capitol on the morning of the inauguration of Barack Obama as the 44th President of the United States.Photograph: Rick Wilking/Reuters